Take a look here, and get out your CMs, or your CM Pros, or even your CM Pro Trigs. Or anything that works.

Shown are the upper walls of a little 2-story place, with a principal pitch of 12:12 bearing on the 4'-0" kneewalls. All rafters are 2x12s.

A shed dormer runs across much of the front and back, each with a different pitch. Front and back wall heights at the shed rafter seats are shown.

The ridge won't be structural, as we will do collar ties as ceiling joists. To get toenail purchase along most of the rafter plumb cuts, we might use an LVL at 16 or 18 deep. But that's overkill, right? How about just a 2x12 with a 2x6 under it? But, ridge doesn't come into play for this question.

Calculate for me the pitches of the shed roof rafters, but please, show me the development of the math. Thanks.

I can work it out graphically with CAD, to get real close, and I get 7.578:12 for the front and 9.016:12 for the rear, but I am wanting to see how math is used to get them exactly.

Shown are the upper walls of a little 2-story place, with a principal pitch of 12:12 bearing on the 4'-0" kneewalls. All rafters are 2x12s.

A shed dormer runs across much of the front and back, each with a different pitch. Front and back wall heights at the shed rafter seats are shown.

The ridge won't be structural, as we will do collar ties as ceiling joists. To get toenail purchase along most of the rafter plumb cuts, we might use an LVL at 16 or 18 deep. But that's overkill, right? How about just a 2x12 with a 2x6 under it? But, ridge doesn't come into play for this question.

Calculate for me the pitches of the shed roof rafters, but please, show me the development of the math. Thanks.

I can work it out graphically with CAD, to get real close, and I get 7.578:12 for the front and 9.016:12 for the rear, but I am wanting to see how math is used to get them exactly.

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